Lubricant



Patented July 4, 1950 LUBRICANT Aaron Wachter and Nathan Stillman,Berkeley,

Callfl, asslgnors to Shell Development Company, San Francisco, Calif., acorporation of Delaware No Drawing. Application August 31, 1948, SerialNo. 47,132

9 Claims. (Cl. 252-51.5)

This invention relates to novel lubricating compositions. Morespecifically, this invention pertains to lubricants, such as minerallubricating oils, synthetic lubricants of hydrocarbon and/ornon-hydrocarbon origin, and the like, containing therein an additivehaving the property, inter alia, of reducing the combustion chamberdeposits in internal combustion engines.

The deleterious effects of combustion chamber deposits in internalcombustion engines are well known. For example, in spark ignitioninternal combustion engines, especially those operating on gasolinescontaining tetra-ethyl lead, deposits are formed which adhere to thevarious parts, such as the spark plugs, valve stems, piston crown, andthe like, of the engine which come in contact with the combustionproducts of such fuels (gasolines), resulting in failure ordeterioration, or both, of the afiected parts. Scavenging agents, suchas ethylene dibromide, normally added to leaded fuels, aid in preventingsuch deposition, but no such agent is known which even substantiallysolves the deposition problem. Engines which operate on non-leadedfuels, such as Diesel engines, also sufier from deposition (of theproducts of combustion) on the various parts of the engine, especiallyin the combustion chamber. Although the nature of the deposits variesaccording to the fuel composition employed, e. g., in spark ignitioninternal combustion engines operating on leaded gasoline the depositscontain a substantial portion of lead compounds, while in spark ignitioninternal combustion engines operating on non-leaded gasoline, and incompression ignition engines, such as Diesel engines, the deposits arelargely carbonaceous in nature, the deleterious effects of all types ofthese deposits are recognized. The use of scavenging agents, asabove-mentioned, which at best are inadequate, the use of specialcleaning solvents, e. g., by flooding the combustion chambers therewith,and mechanical means, such as scraping, both of which latter methodsrequire that the engine be idle, are the chief methods used until nowfor combatting combustion chamber deposits.

An object of this invention is to provide lubricating compositions whicheliminate, or at least materially inhibit and/or reduce, the combustionchamber deposits of internal combustion engines. Another object is toprovide lubricating compositions Which decrease lacquer formation, ringsticking, and bearing corrosion. Other objects and their achievement inaccordance with the present invention will be apparent from thefollowing specification.

It has now been found that the incorporation in lubricants of compoundshaving a nitroso group attached to a nitrogen atomwhich in turn isattached to two hydrocarbon radicals eliminates, or at least materiallyreduces, combustion chamber deposits of internal combustion engines, andpossesses other advantages, as hereinafter more fully described.

The compounds to be incorporated in lubricants to form the lubricatingcompositions of the present invention may be illustrated by the generalformula:

wherein R1 and R2 are hydrocarbon radicals. Suitable radicals include,for example, alkyl, alkenyl, aralkyl, aryl, alicyclic and cyclo-olefinicradicals, such as the methyl, ethyl, propyl, isopropyl, normal butyl,secondary butyl, tertiary butyl, hexyl, iso-octyl, dodecyl, cetyl,stearyl, trimethyl octadecyl, allyl, methallyl, crotyl, oleyl,cyclopentyl, methyl cyclopentyl, cyclohexyl, isopropyl cyclohexyl,endomethylene cyclohexyl. cyclopentenyl, cyclohexenyl, phenyl, tolyl,xylyl, butyl phenyl, naphthyl, anthryl, and the like. R2 may be the sameor different from R1; likewise, R1 and R2 may be connected to form aring, together with the nitrogen atom which is also attached to thenitroso group.

Preferably, the present compounds are those wherein the total number ofcarbon atoms in both R1 and R2 is from about 5 to about 40, andpreferably from 6 to about 20. Dicyclohexyl nitrosamine, illustratessuch a compound, and when incorporated in a lubricant, forms therewith apreferred lubricating composition of the present invention. Othercompounds which illustrate the additives of the present invention aredi-isopropyl nitrosamine, di-n-butyl nitrosamine, di-n-propylnitrosamine, diisopropyl nitrosamine, methylpentyl nitrosamine,methylcyclohexyl nitrosamine, diphenyl nitrosamine,bis(3,3,5-trimethyl-cyclohexyl) nitrosamine, methylbenzyl nitrosamine,allylbutyl nitrosamine, n-propylcyclohexenyl nitrosamine, and the like.

As above stated, it is essential to the success of the present inventionthat additives incorporated in lubricants to form the lubricatingcompositions of the present invention have a nitroso group attached to antirogen atom which in turn is attached to two hydrocarbon radicals.Thus, while there is relatively a wide latitude of choice in theselection of the radicals, the limitation being that the total number ofcarbon atoms in the molecule be at least about 5 and not more than about40, they must be attached to a =NN=O group in order to achieve theadvantages of the present invention.

In preparing the compositions of the present invention one or more ofthe above-described compounds is incorporated in a liquid lubricantwhich will generally have a minimum boiling point of about 700 F. and aviscosity of at least about Saybolt units at 100 F., and preferablyhigher, such as a mineral lubricating oil,

synthetic lubricant of hydrocarbon or non-hydrocarbon origin, and thelike. Preferably, the present additives are dissolved in the lubrieatingoil. In order to impart a substantial oil solubility to the presentcompounds, the total number of carbon atoms in R1 and R2 of the abovegeneral formula is preferably at least 5, and preferably the totalnumber is less than about 40. However, the present nitroso compounds maybe dispersed or emulsified in the lubricant where necessary ordesirable, in which case emulsifying agents, such as triethanolamineoleate, sodium oleate, the alkali metal sulfonates, and the like, may beemployed if desired. Solutizers may also advantageously be employed insome instances. The quantity of the present additives to be incorporatedin lubricants may be varied between about .001% and about 5% by weight,and good results obtained therewith, but preferably from about 0.01% toabout 0.3% by weight is employed, since excellent results areeconomically obtained therewith. However, larger or smaller amounts ofthe additive, or mixtures thereof, may also be used.

Other additives which impart special properties to the lubricatingcomposition may; be incorporated in the present compositions wheredesirable. For example, pour point depressants, viscosity indeximprovers, oiliness carriers, and the like, may be incorporated in thecompositions of the present invention without adversely affecting theaction of the additives of the present invention, and the beneficialeffects of such additional additives are obtained.

The following examples illustrate the compositions and process of engineoperation in accordance with the present invention, which is not to beconsidered as limited thereby.

Example I Various quantities of dicyclohexyl nitrosamine were dissolvedin a mineral lubricating oil of S. A. E. grade 60. These compositionswere tested in a Lauson supercharged engine (spark ignition, liquidcooled engine of 2.600 inch bore and 2 inch stroke) operated at 2050 R.P. M. under a load of 5.0 B. H. P. for hours on a 100 octane leadedgasoline. The following results, as compared to those obtained with thesame oil without the additive, were obtained:

With the lubricating oil containing 0.03% by weight of dicyclohexylnitrosamine deposits at the top ring groove were reduced by 25%, andlacquer on the piston skirt (the area below the piston rings in contactwith the walls of the combustion chamber) was decreased by about 13%;lacquer on the piston undercrown was light and covered only about 25% ofthe total area, as compared to 100% of the area covered with a mediumlacquer deposit observed in the absence of the additive. The combustionchamber deposits, as indicated by the deposition on the piston crown,was greatly decreased by the presence of the additive in the oil, andthe small amount of deposits present were smooth and soft, instead ofbeing rough, hard and uneven, as observed when operating on the same oilwithout the additive.

With the lubricating oil containing 0.1% by weight of dicyclohexylnitrosamine,substantially similar results as the above were obtained.Especially notable, however, was the reduction of combustion chamberdeposits.

Example [I Dicyclohexyl nitrosamine, 0.1% by weight, was dissolved in anS. A. E. grade 30 lubricating oil,

and the resulting composition tested in a Caterpillar 4 cylinder, liquidcooled, Diesel engine having a bore of 4 inches and a stroke of 5%inches operating at 1400 R. P. M. for 120 hours on a regular Dieselfuel.

Bearing weight loss, as compared to the loss when operating on the samelubricating oil without the additive, was reduced by 87.5%. The generalengine cleanliness was greatly improved by the presence of the additive.

Example III Example I was repeated using as the lubricant an S. A. E.grade 60 oil containing 0.25% by weight of the calcium salt of thecondensation product of an alkylphenol and formaldehyde, calculated asthe sulfate ash, and 0.05% by weight of the calcium salts of oil solublepetroleum sulfonic acids, calculated as the sulfate ash, and the samelubricating composition containing 0.1% by weight of dicyclohexylnitrosamine.

Results were substantially as described for Example I, the reduction incombustion chamber deposits observed when employing the oil containingdicyclohexyl nitrosamine being especially marked.

Example IV The same lubricating compositions of Example Ill were testedin 8. Franklin aircraft 4 cylinder, spark ignition, air cooled engine,having a 4 inch bore and 3 inch stroke, and operated at 2200 R. P. M.with a load of 37 B. H. P. for 50 hours on an octane grade leaded fuel.

Combustion chamber deposits, without the presence of dicyclohexylnitrosamine, were heavy, and were greatly reduced when the oilcontaining dicyclohexyl nitrosamine was employed. As further indicativeof this beneficial effect, without the presence of dicyclohexylnitrosamine in the lubricant the spark plugs became fouled in 7 hours,while with the oil containing the additive no fouling was observed overthe entire time of the run, 50 hours.

Example V Dicyclohexyl nitrosamine, 0.1% by weight, was dissolved in anS. A. E. grade 30 lubricating oil,

and the resulting composition tested in a Chevro- Example VI Comparativedata were obtained with different lubricating compositions on a CUE(Wright cylinder) spark ignition, air cooled engine having a bore of6.125 inches and a stroke of 6.875 inches, operating at 1800 R. P. M.for hours on a 100 octane leaded gasoline. Both lubricants were S. A. E.grade 60 oil, one containing 0.25% by weight of the calcium salt of thecondensation product of an alkylphenol and formaldehyde, calculated asthe sulfonate ash and. 0.05% by weight of the calcium salts of oilsoluble petroleum sulfonic acids, calculated as the sulfate ash, and thesame lubricating composition containing 0.1% by weight of dicyclohexylnitrosamine.

By operation with the lubricant containing the dicyclohexyl nitrosamine,as compared to the same lubricant minus this additive, lacquerdeposition on the piston was decreased by l%,

thereby giving a substantially cleaner piston, 8

combustion chamber deposits as indicated by deposition in the top ringgroove was reduced by 37%, and combustion chamber deposition as visuallyobserved was substantially less, and the deposits which formed were of asoft, smooth character, as compared to the hard, uneven and brittledeposits otherwise obtained.

, Example VII amine, diisopropyl nitrosamine and N-nitroso 90 di-(1,3-dimethylbutyl) amine. Although the ad-' vantageous results describedin Example I were generally observed, the compounds were especiallyefficacious in reducing combustion chamber deposits. I

Other additives which havea nitroso group attached to a nitrogen atomwhich in turn is attached to two hydrocarbon radicals, as defined I andillustrated hereinbefore, may be substituted amines therein employed.which latter nitrosamines represent preferred materials selected toillustrate the present invention, and under sub-* stantially the sameoperating conditions results amples are obtained. I

In the above examples, a significant and unobvious advantage obtained 1;engine operation in accordance with the present invention is thedecrease in deposition in both spark ignition engines operating onleaded fuels, and in compression ignition engines operating on nonleadedfuels, as demonstrated in the above examples. A further advantage is thechange in ,in the above examplesfor the various nitroscomparable tothose described in the above ex- 85 properties of the combustion chamberdepositsquent cycles. whereas the soft deposit does not 5 so tend tocause pre-ignition.

In order to demonstrate specificity of the present class of lubricantadditives, Example I was repeated using 0.1% by weight of dicyclohexylamine in place of the dicyclohexyl nitrosamine.

No reduction in combustion chamber deposits over the oil containing noadditive was observed, while a heavier lacquer coating was formed on thepiston shirt.

The foregoing examples demonstrate the surprising reduction ofcombustion chamber deposits, among the other advantages, obtained inaccordance with the present invention, by incorporating into lubricantsfor internal combustion engines only relatively small amounts ofcompounds having a nitroso group attached to a nitrogen atom which inturn is attached to an organic radical. The use of the presentlubricating compositions in the operation of internal combustion enginesconstitutes a new process 7 for. the operation thereof, which process iswithin the scope of the present invention.

The present application is a continuation-inpart of the copendingapplication Serial No. 663,608, filed April 19, 1946.

We claim as our invention:

.1. A lubricant comprising a predominant amount of a mineral lubricatingoil and from about 0 to about 5% by weight of a compound having theformula wherein R1 and R2 are hydrocarbon radicals having a total offrom 6 to about 20 carbon atoms.

'2. A lubricant comprising a predominant amount'of a mineral lubricatingoil having a minimum boiling temperature of about 700 F. and from about0.01% to about 0.3% by weight of dicyclohexyi nitrosamine.

3; A lubricant comprising a predominant amount of a mineral lubricatingoil and from about 0.001% to about 5% by weight of dicyclohexylnitrosamine.

4. A" lubricant comprising a predominant amount of a mineral lubricatingoil having a minimum boiling temperature of about 700 F. and from about0.01% to about 0.3% by weight of diisopropyl nitrosamine.

5. A lubricant comprising a predominant amount of a mineral lubricatingoil and from about 0.001% to about 5% by weight of diisopropylnitrosamine.

6. A lubricant comprising a predominant amount of a mineral lubricatingoil having a minimum boiling temperature of about 700 1''. and fromabout 0.01% to about 0.3% by weight of N-nitroso diphenylamine.

7. A lubricant comprising a predominant amount of a mineral lubricatingoil and from about'0.001% to about 5% by weight of N-nitrosodiphenylamine.

nmnunons The following references are of in the ille of this patent:

UNITED STATES PATENTS Number Name Date 2,009,818 Sa'lzberg July 30, 19352,109,164 Clifford Feb. 22, 1938 2,189,788 Freeman Feb. 13, 1940 OTHERREFERENCES Lubrication of Industrial and Marine Machinery, by Forbes;John Wiley and Sons, 1945 (2nd printing), page 11 pertinent.

Lubitext, DG-4A, publication by Esso Marketeers, 1939, page 19 andDG-4Al. page 8.

1. A LUBRICANT COMPRISING A PREDOMINANT AMOUNT OF A MINERAL LUBRICATINGOIL AND FROM ABOUT 0.001% TO ABOUT 5% BY WEIGHT OF A COMPOUND HAVING THEFORMULA